This page shows details and results of our analysis on the malware W32/

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Threat Detail

  • Malware Type: Virus
  • Malware Sub-type: Parasitic
  • Protection Added: 2007-08-31

This description is for a file infecting virus which searches for executable files on the infected machine to prepend its viral code.

Apart from this, it also drops other malware, which inturn download password stealing trojans from various websites.

The characteristics of this virus with regards to file names/folders created will differ depending on the way in which the attacker had configured it. Hence, this is a general description.

Minimum Engine


File Length

59,682 bytes

Description Added


Description Modified


Malware Proliferation

When executed, this virus drops the following files:

  • %System%\Richdll.dll (Detected as W32/HLLP.Philis.dll)
  • %System%\Uninstall\rundll32.exe (Copy of itself)

It then creates the following registry entries:

  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    Data: Load = "C:\Windows\Uninstall\rundll32.exe"
    Data: auto = "1"

The dropped dll file named RichDll.dll then injects itself into Explorer.exe and IExplore.exe and attempts to download other file from the following location:

  • www2.[removed].cn

This site hosts password stealing Trojans, typically from PWS-Lineage and PWS-WOW family.


  • %System% refers to a variable system location
  • Software based firewall on the infected machine will not alert about the virus
    trying to connect to the internet. This is because, the virus injects itself into
    IExplore.exe and Explorer.exe to connect to the internet
  • The downloaded password stealers may download/drop other executables

The virus, then searches for executable files and prepends its viral code to target files.

The virus creates files with the name "_desktop.ini" in every folder where an infection takes place. This is created as a hidden system file and contains the date on which virus was executed to visit the folder in which the file resides. The date is shown in yyyy/mm/dd format.

The virus tries to spread via existing network shares. It searches for all active machines within the subnet. When it finds an active machine it sends an ICMP ping request and waits for a response. After getting the ping response it tries to access the ADMIN$, IPC$ and any other shares that might exist on the machine.

If the virus is able to access a shared resource, it first copies "_desktop.ini" to the root of the share to mark the share as visited and then infects executables present in the share.

While infecting executables via a network share the virus does not limit itself to infecting specific file names as mentioned above. In the case of a shared printer, the virus's infection routine effectively creates printer job to print the date as contained in "_desktop.ini" file that the virus tries to copy.

  • Presence of files and registry entries mentioned earlier
  • Presence of hidden system files named _desktop.ini in many folders
  • Increase in size of EXE files
  • Increase in disk activity due to read and write operations


This is a file infecting virus, and infection starts with manual execution of the binary. It may rely on improperly configured shares to spread.

This virus may also be received as a result of poor security practices, or un-patched machines and vulnerable systems. Distribution channels include IRC, peer-to-peer networks, email, newsgroups postings, etc.



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